Encapsulated materials have been used for many years in a wide variety of commercial applications. U.S. Pat. No. 3,016,308 discloses one of the early efforts using encapsulated material as the image source on recording paper. U.S. Pat. Nos. 4,058,434 and 4,201,404 show other methods of application of encapsulated coloring materials on paper substrates to be used as imaging media and the like. In addition to release of physically observable materials such as ink in order to form a visible image, other types of active ingredients such as odor releasing materials, bacteriostatic materials, chemically active materials and the like have been provided in encapsulated form.
A wide variety of processes exist by which microcapsules can be manufactured. These varied processes provide different techniques for producing capsules of varying sizes, alternative materials for the composition of the capsule shell, and various different functional materials within the shell. Some of these various processes are shown in U.S. Pat. Nos. 3,516,846; 3,516,941; 3,778,383; 4,087,376; 4,089,802; 4,100,103 and 4,251,386 and British patent specification Nos. 1,156,725; 2,041,319 and 2,048,206. A wide variety of different materials may be used in making the capsule shells, including gelatin and synthetic polymeric materials. A popular material for shell formation is the polymerization reaction product between urea and formaldehyde or melamine and formaldehyde, or the polycondensation products of monomeric or low molecular weight polymers of dimethylolurea or methylolated urea with aldehydes. A variety of capsule forming materials are disclosed, for example, in U.S. Pat. Nos. 3,516,846 and 4,087,376 and British patent specification Nos. 2,006,709 and 2,062,570.
As shown in these references, the principal utility of microencapsulated materials is in the formation of a surface coated with the microcapsules dispersed in a binder. The microcapsules are rupturable by various means to release the material contained therein. U.S. Pat. No. 4,493,869 discloses a means of releasing liquid from a rupturable microcapsule by pressure or applied shear to the capsule layer, e.g., by scratching or scraping as with a fingernail.
It has been desired to employ appliques bearing rupturable microcapsules as a means for enhancing clothing, such as, for example, T-shirts Several problems exist with respect to providing microcapsule-bearing appliques that can easily be applied to the fibrous materials of clothing. First, the appliques must be easily printable by the manufacturer thereof. Second, the appliques and the microcapsules associated therewith must be resistant to washing conditions encountered in a typical washing machine.
Patches made of fabric material impregnated with cross-linkable or waterproof binders and microcapsules and having a hot melt adhesive on one surface have been used as iron-on appliques. These patches are difficult to print with high resolution due to their fibrous and porous nature. When processed on web fed equipment they are difficult to die cut to the shape of the design without special catching and packaging equipment; hence, they are often made in sheet form with the ultimate user cutting out the patch for application, generally resulting in a patchy appearance to the applique. Iron-on applqques made from flocked fibers, silk screen printed and coated with a hot melt adhesive and used as a transfer material are available, but they do not contain microcapsules, and are expensive to produce. Transfer decals made as iron-on transfers and composed of vinyl plastisol inks are available, but they also do not contain microcapsules or other means for imparting fragrances and the like.